This invention relates to cutting elements for use in a rock bit and more specifically to cutting elements which have a cutting table made up of segments of an ultra hard material.
A cutting element, such as a shear cutter shown in FIG. 1, typically has a cylindrical tungsten carbide substrate body 10 which has a cutting face 12. An ultra hard material cutting table 14 (i.e., layer) is bonded onto the substrate by a sintering process. The ultra hard material layer is typically a polycrystalline diamond or polycrystalline cubic boron nitride layer. During drilling, cracks form on the polycrystalline ultra hard material layer. These cracks are typically perpendicular to the earth formation being drilled. These cracks grow across the entire ultra hard material layer causing the failure of the layer and thus of the cutter. Growth of these cracks result in chipping, laminar type spalling and exfoliation. As such, there is a need for a cutting element having a cutting table that is capable of resisting crack growth.